Python_day2

循环语句 while for

i = 0
while i < 10:
	score = int(input('请输入一个成绩:'))
	
	if score > 100 or score < 0:
		break
		# continue
	else:
		score //= 10
		if score == 9 or score == 10:
			print('A')
		elif score == 8:
			print('B')
		elif score == 7:
			print('C')
		elif score == 6:
			print('D')
		else:
			print('E')
	i += 1
else:
	print("10个成绩判断完成")

　　练习1:读入一个整型数，将其每一位倒序输出,不允许转换为字符串 1998

n = int(input('整型数:'))
while n > 0:
	print(n % 10)
	n = n // 10

　　练习2：将读入字符串的每一个成员倒序输出

s = input('请输入一个字符串:')
i = len(s)-1
while i >= 0:
	print(s[i])
	i -= 1

i = -1
while i >= -len(s):
	print(s[i])	
	i -= 1

　　控制语句

判断用户输入的年份是否为闰年，闰年能被4整除并且不能被100整除，或者能被400整除的

year = int(input('年份:'))
if year % 4 == 0 and year % 100 != 0 or year % 400 == 0:
	print('{}是闰年'.format(year))
else:
	print('{}是平年'.format(year))

　　多个条件:输入一个月份，判断其所属季节

month = int(input('月份:'))
if month < 1 or month > 12:
	print('无效月份')
elif 3 <= month <= 5:
	print('春天')  
elif 6 <= month <= 8:
	print('夏天')
elif month >= 9 and month <= 11:
	print('秋天')
else:
	print('冬天')

　　

读入一个成绩，判断其所属等级
90~100 A
80～89 B
70～79 C
60～69 D
0～59 E

if score > 100 or score < 0:
	pass（空段）
else:
	score //= 10
	if score == 9 or score == 10:
		print('A')
	elif score == 8:
		print('B')
	elif score == 7:
		print('C')
	elif score == 6:
		print('D')
	else:
		print('E')

　for...in循环　

for i in range(10):
	print(i)

i = 0
while i < 10:
	print(i)
	i += 1

print('*******************************')
for i in range(5, 10):
	print(i)
i = 5
while i < 10:
	print(i)
	i += 1

print('*******************************')
for i in range(10, 5, -1):
	print(i)
i = 10
while i > 5:
	print(i)
	i -= 1

print('*******************************')

　　遍历字符串

for i in 'python':
	print(i)

　　练习题

'''
练习1:读入两个整型数，求得两个数中较大的一个
'''

num1, num2 = eval(input('读入两个整型数:'))
if num1 > num2:
	print(num1)
else:
	print(num2)

'''
练习2:读入一个字符串，不使用len函数，求得字符串的长度
'''

s = input('请输入一个字符串:')
n = 0
for i in s:
	n += 1
print('字符串{}的长度是{}'.format(s, n))

'''
练习3:打印99乘法表
'''

for i in range(1, 10): # row
	for j in range(1, i+1): # col
		print('{}*{}={:<2}'.format(j, i, j*i), end=' ')
	print()


'''
练习4:读入一个整型数，判断其是否为质数(除了1和本身不能被其它数整除的数)
'''
n = int(input('整数:'))
prime = True

i = 2
while i < n:
	if n % i == 0:
		prime = False	
		break
	i += 1
if prime:
	print('yes')
else:
	print('no')